Depth data measuring head, measuring apparatus, and measuring method

Abstract

Disclosed are a depth data measuring head, a measuring device and a measuring method. The measuring head comprises: a projection device for projecting linear light to an imaging area; an image sensor comprising N memory cell sets, each memory cell set exposed in an exposure switch cycle te that is phase-shifted by 2π/N relative to each other. The projection device completes a single pattern scan within a scanning cycle , which includes multiple repeating subcycles , in each subcycle , a projection cycle tp includes N waveform projection areas with a width of 2π/N and light intensity encoded based on the imaging pattern. Therefore, when a pattern scan is completed within the scanning cycle , each of the N N memory cell sets of the image sensor images a different striped-light pattern, and there is a phase shift of 2π/N between the N striped-light patterns. The present invention can realize the acquisition of multiple images of a single linear light scan, greatly improve the synthesis speed of the depth map, and is suitable for capturing a moving target object.

1 . A depth data measuring head, comprising:
 a projection device for projecting linear light that moves in a first direction to an imaging area, wherein the length of the linear light is in a second direction perpendicular to the first direction;   an image sensor including N memory cell sets, each memory cell set exposed in an exposure switch cycle t e  that is phase-shifted by 2π/N relative to each other, where N is an integer greater than 1,   wherein the projection device completes a single pattern scan within a scanning cycle  , which includes multiple repeating subcycles  , in each subcycle  , the linear light changes brightness with a projection cycle t p , which has the same duration as the exposure switch cycle t e , the projection cycle t p  includes N waveform projection areas, each with a width of 2π/N, where the light intensity in each waveform projection area is encoded such that when a single pattern scan is completed within the scanning cycle  , the N memory cell sets in the image sensor each capture a different striped-light pattern, the N striped-light patterns form a set of N-step phase-shifted patterns, each having a phase-shifted of 2π/N relative to the others.   
     
     
         2 . The depth data measuring head according to  claim 1 , wherein the projection cycle t p  of the linear light is synchronized with the exposure switch cycle t e  of the first memory cell set of the N memory cell sets. 
     
     
         3 . The depth data measuring head according to  claim 1 , wherein N=2 n , and n is an integer greater than or equal to 1. 
     
     
         4 . The depth data measuring head according to  claim 1 , wherein each waveform projection area corresponds to a projected rectangular wave with a width of 2π/N or 0, and based on the light intensity distribution of the set of N-step phase-shifted patterns corresponding to the subphase  , the light intensity of each waveform projection area is determined. 
     
     
         5 . The depth data measuring head according to  claim 4 , wherein the set of N-step phase-shifted patterns is a sine wave four-step phase-shifted pattern, and the light intensity value of each waveform projection area in each projection cycle t p  is obtained based on the exposure of N memory cell sets corresponding to the waveform projection area, wherein the light intensity value is not less than zero. 
     
     
         6 . The depth data measuring head according to  claim 1 , wherein the dwell time t c  corresponding to the linear light scanning on each column of pixels is not less than the quotient of the scanning cycle   divided by the number of columns C, and the dwell time t c  is more than 10 times the projection cycle t p . 
     
     
         7 . The depth data measuring head according to  claim 5 , wherein in each subphase T i , the linear light is projected m times with the projection cycle t p , and the duration of each subphase T i  is greater than the dwell time t c . 
     
     
         8 . The depth data measuring head according to  claim 1 , wherein each pixel in the image sensor includes N memory cells, and each of the N memory cells of a pixel belongs to one of the N memory cell sets. 
     
     
         9 . The depth data measuring head according to  claim 8 , wherein the N memory cells included in each pixel are N charge memory cells, and the exposure positions of the N charge memory cells corresponding to one pixel are the same, but the exposure cycles are phase-shifted 2π/N from each other, and
 when a single pattern scan is completed within the scanning cycle  , the set of N-step phase-shifted patterns are obtained from the N sets of charge memory cells, and the set of N-step phase-shifted patterns is used to generate one depth map of the imaging area. 
 
     
     
         10 . The depth data measuring head according to  claim 1 , wherein the image sensor includes N sets of uniformly distributed pixels on the imaging surface, each pixel having one corresponding memory cell, when a single pattern scan is completed within the scanning cycle  , the set of N-step phase-shifted patterns is obtained from the N memory cell sets corresponding to the N pixel sets, and the set of N-step phase-shifted patterns is used to generate one depth map of the imaging area. 
     
     
         11 . The depth data measuring head according to  claim 1 , wherein the projection device completes a single pattern scan in a first scanning cycle   such that the N memory cell sets in the image sensor each capture a different striped-light pattern, and the N striped-light patterns form a set of Gray code patterns,
 the projection device completes another single pattern scan in a second scanning cycle  , such that the N memory cell sets each capture a different striped-light pattern, and the N striped-light patterns form the set of N-step phase-shifted pattern, 
 wherein based on the set of Gray code patterns, one depth map of the imaging area is generated from the set of N-step phase-shifted patterns. 
 
     
     
         12 . The depth data measuring head according to  claim 1 , wherein the projection device includes: a light-emitting device for generating linear light; and
 a reflecting device for reflecting the linear light, thereby projecting the linear light moving in a direction perpendicular to the stripe direction to the capturing area at a predetermined frequency, the length direction of the linear light is the length direction of the projected striped light, and the reflecting device includes one of the following:   a mechanical galvanometer that vibrates back and forth at the predetermined frequency;   a micromirror device that reciprocates at the predetermined frequency; and   a mechanical rotating mirror that rotates unidirectionally at the predetermined frequency.   
     
     
         13 . The depth data measuring head according to  claim 1 , wherein the image sensor includes a first image sensor and a second image sensor whose relative positions are fixed, wherein the first image sensor and the second image sensor each include the N memory cell sets and are exposed synchronously with each other. 
     
     
         14 . The depth data measuring head according to  claim 1 , wherein the projection device completes α pattern scans within α scanning cycles  , each of the scanning cycle   includes multiple repeating subcycles  , each subcycle   includes N subphases T 1 -T N , and in each subphase T i , the linear light is projected with brightness changes at the projection cycle t p , the duration of the projection cycle t p  is the same as the duration of the exposure switch cycle t e , and the projection cycle t p  includes a bright area, wherein, in the subphases T 1 -T N , the position of the bright area in the projection cycle t p  changes at an interval of 2π/αN phase, so that when a single pattern scan is completed within each scanning cycle  , the N memory cell sets of the image sensor each image a different striped-light pattern, and when α pattern scans are completed within α scanning cycles  , αN striped light patterns constitute a set of αN step phase-shifted patterns with a 2π/αN phase-shifted between each other, wherein α is an integer greater than or equal to 2. 
     
     
         15 . The depth data measuring head according to  claim 1 , wherein each subcycle   includes N subphases T 1 -T N , and in each subphase T i , the linear light is projected with brightness changes at the projection cycle t p , the duration of the projection cycle t p  is the same as the duration of the exposure switch cycle t e , and the projection cycle t p  includes a bright area, wherein, in the subphases T 1 -T N , the position of the bright area in the projection cycle t p  changes at an interval of 2π/N phase, so that when a single pattern scan is completed within each scanning cycle  , the N memory cell sets of the image sensor each image a different striped-light pattern, and the N striped-light patterns constitute the set of N-step phase-shifted patterns with a 2π/N phase-shifted between each other. 
     
     
         16 . A depth data measuring device, comprising:
 a depth data measuring head, comprising:
 a projection device for projecting linear light that moves in a first direction to an imaging area, wherein the length of the linear light is in a second direction perpendicular to the first direction; 
 an image sensor including N memory cell sets, each memory cell set exposed in an exposure switch cycle t e  that is phase-shifted by 2π/N relative to each other, where N is an integer greater than 1, 
 wherein the projection device completes a single pattern scan within a scanning cycle  , which includes multiple repeating subcycles  , in each subcycle  , the linear light changes brightness with a projection cycle t p , which has the same duration as the exposure switch cycle t e , the projection cycle t p  includes N waveform projection areas, each with a width of 2π/N, where the light intensity in each waveform projection area is encoded such that when a single pattern scan is completed within the scanning cycle  , the N memory cell sets in the image sensor each capture a different striped-light pattern, the N striped-light patterns form a set of N-step phase-shifted patterns, each having a phase-shifted of 2π/N relative to the others; and 
   a processor connected to the depth data measuring head, configured to obtain one depth map of the imaging area from the obtained N striped-light patterns when completing a single pattern scan within the scanning cycle  .   
     
     
         17 . The depth data measuring device according to  claim 16 , wherein the depth data measuring head includes: a first depth imaging measuring head and a second depth imaging measuring head whose relative positions are fixed,
 wherein after the first depth imaging measuring head completes a first pattern scan, the second depth imaging measuring head performs a second pattern scan, and a first set of N-step phase-shifted patterns obtained by the first pattern scan and a second set of N-step phase-shifted patterns obtained by the second pattern scan are synthesized into depth information of an object to be imaged in an imaging area based on the relative position.   
     
     
         18 . A depth data measuring method, comprising:
 projecting linear light that moves in a first direction to an imaging area, wherein the length of the linear light is in a second direction perpendicular to the first direction, linear light projection completes a single pattern scan in one scanning cycle  , which includes multiple repeating subcycles  , in each subcycle  , the linear light changes brightness with a projection cycle t p , which has the same duration as the exposure switch cycle t e , the projection cycle t p  includes N waveform projection areas, each with a width of 2π/N, where the light intensity in each waveform projection area is encoded, where N is an integer greater than 1;   capturing the imaging area using an image sensor including N memory cell sets to obtain N image frames under the linear light scanning projection, each memory cell set exposed in an exposure switch cycle t e  that is phase-shifted by 2π/N relative to each other; and   obtaining depth data of the object to be measured in the imaging area based on the image frames,   wherein the light intensity in each waveform projection area is encoded such that when a single pattern scan is completed within the scanning cycle  , the N memory cell sets in the image sensor each capture a different striped-light pattern, the N striped-light patterns form a set of N-step phase-shifted patterns, each having a phase-shifted of 2π/N relative to the others.   
     
     
         19 . The depth data measuring method according to  claim 18 , wherein the depth data measuring head includes a first depth imaging measuring head and a second depth imaging measuring head whose relative positions are fixed, and the method includes:
 using a first depth imaging measuring head of a depth data measuring device to perform a first pattern scan on an imaging area to obtain a first set of N-step phase-shifted patterns;   using a second depth imaging measuring head of the depth data measuring device to perform a second pattern scan on the imaging area to obtain a second set of N-step phase-shifted patterns;   synthesizing depth information of an object to be imaged in the imaging area from the first set of N-step phase-shifted patterns and the second set of N-step phase-shifted patterns based on the relative positions of the first depth imaging measuring head and the second depth imaging measuring head.   
     
     
         20 . The method according to  claim 19 , further includes:
 the depth data measuring device captures multiple sets of first set N-step phase-shifted patterns and multiple sets of second set N-step phase-shifted patterns in relative motion with respect to the object to be imaged; and   synthesizes the depth information generated from the multiple sets of first set N-step phase-shifted patterns and multiple sets of second set N-step phase-shifted patterns into the model information of the object to be imaged based on a calibration point.